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Two words are $k$-binomially equivalent if each subword of length at most $k$ occurs the same number of times in both words. The $k$-binomial complexity of an infinite word is a counting function that maps $n$ to the number of $k$-binomial…

Combinatorics · Mathematics 2022-12-07 Michel Rigo , Manon Stipulanti , Markus A. Whiteland

Let $D^+$ be the first octant of the Euclidean space and consider the integral cube grid $G$ in $D^+$. The intersections of each line with $G$ form an infinite sequence of three letters which can be considered as an extension of well-known…

Combinatorics · Mathematics 2017-09-13 Mahdi Saleh , Majid Jahangiri

We study the set of finite words with zero palindromic defect, i.e., words rich in palindromes. This set is factorial, but not recurrent. We focus on description of pairs of rich words which cannot occur simultaneously as factors of a…

Combinatorics · Mathematics 2018-01-09 Edita Pelantová , Štěpán Starosta

Two finite words $u$ and $v$ are called Abelian equivalent if each letter occurs equally many times in both $u$ and $v$. The abelian closure $\mathcal{A}(\mathbf{x})$ of (the shift orbit closure of) an infinite word $\mathbf{x}$ is the set…

Combinatorics · Mathematics 2021-08-04 Svetlana Puzynina , Markus A. Whiteland

We prove new results concerning the relation between bifix codes, episturmian words and subgroups offree groups. We study bifix codes in factorial sets of words. We generalize most properties of ordinary maximal bifix codes to bifix codes…

Prefix normal words are binary words that have no factor with more $1$s than the prefix of the same length. Finite prefix normal words were introduced in [Fici and Lipt\'ak, DLT 2011]. In this paper, we study infinite prefix normal words…

Combinatorics · Mathematics 2021-05-31 Ferdinando Cicalese , Zsuzsanna Lipták , Massimiliano Rossi

We introduce and study a complexity function on words $c_x(n),$ called \emph{cyclic complexity}, which counts the number of conjugacy classes of factors of length $n$ of an infinite word $x.$ We extend the well-known Morse-Hedlund theorem…

Formal Languages and Automata Theory · Computer Science 2016-06-29 Julien Cassaigne , Gabriele Fici , Marinella Sciortino , Luca Q. Zamboni

A word $w$ is said to be closed if it has a proper factor $x$ which occurs exactly twice in $w$, as a prefix and as a suffix of $w$. Based on the concept of Ziv-Lempel factorization, we define the closed $z$-factorization of finite and…

Combinatorics · Mathematics 2021-06-08 Marieh Jahannia , Morteza Mohammad-noori , Narad Rampersad , Manon Stipulanti

We introduce the notion of $\alpha$-numbers and formal intercept of sturmian words, and derive from this study general factorisations formula for sturmian words. Sturmian words are defined as infinite words with lowest unbound complexity,…

Combinatorics · Mathematics 2025-04-21 Caius Wojcik

Frid, Puzynina and Zamboni (2013) defined the palindromic length of a finite word $w$ as the minimal number of palindromes whose concatenation is equal to $w$. For an infinite word $u$ we study $PL_{u}$, that is, the function that assigns…

Combinatorics · Mathematics 2018-08-28 Petr Ambrož , Edita Pelantová

A prefix normal word is a binary word with the property that no substring has more 1s than the prefix of the same length. This class of words is important in the context of binary jumbled pattern matching. In this paper we present an…

Data Structures and Algorithms · Computer Science 2014-06-23 Péter Burcsi , Gabriele Fici , Zsuzsanna Lipták , Frank Ruskey , Joe Sawada

In 2013, Fici and Zamboni proved a number of theorems about finite and infinite words having only a small number of factors that are palindromes. In this paper we rederive some of their results, and obtain some new ones, by a different…

Formal Languages and Automata Theory · Computer Science 2020-01-07 Lukas Fleischer , Jeffrey Shallit

In this paper, we study combinatorial and structural properties of a new class of finite and infinite words that are 'rich' in palindromes in the utmost sense. A characteristic property of so-called "rich words" is that all complete returns…

Combinatorics · Mathematics 2010-03-16 Amy Glen , Jacques Justin , Steve Widmer , Luca Q. Zamboni

The paper explores combinatorial properties of Fibonacci words and their generalizations within the framework of combinatorics on words. These infinite sequences, measures the diversity of subwords in Fibonacci words, showing non-decreasing…

Combinatorics · Mathematics 2025-04-10 Jasem Hamoud , Duaa Abdullah

Return words constitute a powerful tool for studying symbolic dynamical systems. They may be regarded as a discrete analogue of the first return map in dynamical systems. In this paper we investigate two abelian variants of the notion of…

Combinatorics · Mathematics 2012-04-27 Svetlana Puzynina , Luca Q. Zamboni

We regard a finite word $u=u_1u_2\cdots u_n$ up to word isomorphism as an equivalence relation on $\{1,2,\ldots, n\}$ where $i$ is equivalent to $j$ if and only if $x_i=x_j.$ Some finite words (in particular all binary words) are generated…

Combinatorics · Mathematics 2014-04-04 Tero Harju , Mari Huova , L. Q. Zamboni

We present a new class of binary words: the prefix normal words. They are defined by the property that for any given length $k$, no factor of length $k$ has more $a$'s than the prefix of the same length. These words arise in the context of…

Formal Languages and Automata Theory · Computer Science 2018-06-01 Gabriele Fici , Zsuzsanna Lipták

The avoidability, or unavoidability of patterns in words over finite alphabets has been studied extensively. A word (pattern) over a finite set is said to be unavoidable if, for all but finitely many words, there exists a morphism mapping…

Formal Languages and Automata Theory · Computer Science 2019-07-16 Paul Sauer

We investigate abelian repetitions in Sturmian words. We exploit a bijection between factors of Sturmian words and subintervals of the unitary segment that allows us to study the periods of abelian repetitions by using classical results of…

Formal Languages and Automata Theory · Computer Science 2013-05-10 Gabriele Fici , Alessio Langiu , Thierry Lecroq , Arnaud Lefebvre , Filippo Mignosi , Élise Prieur-Gaston

Sturmian words form a family of one-sided infinite words over a binary alphabet that are obtained as a discretization of a line with an irrational slope starting from the origin. A finite version of this class of words called Christoffel…

Formal Languages and Automata Theory · Computer Science 2025-07-22 Abhishek Krishnamoorthy , Robinson Thamburaj , Durairaj Gnanaraj Thomas